---
name: "libressl-EVP_PKEY_encrypt"
section: "3"
platform: "linux"
package: "libressl"
version: "4.4.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/libressl-EVP_PKEY_encrypt"
---

# libressl-EVP\_PKEY\_encrypt(3)

encrypt using a public key algorithm

## NAME

**EVP\_PKEY\_encrypt\_init**, **EVP\_PKEY\_encrypt** – encrypt using a public key algorithm

## SYNOPSIS

Crypto Library (libcrypto, -lcrypto)

**#include \<openssl/evp.h\>**

*int*\

**EVP\_PKEY\_encrypt\_init**(*EVP\_PKEY\_CTX \*ctx*);

*int*\

**EVP\_PKEY\_encrypt**(*EVP\_PKEY\_CTX \*ctx*, *unsigned char \*out*, *size\_t \*outlen*, *const unsigned char \*in*, *size\_t inlen*);

## DESCRIPTION

The **EVP\_PKEY\_encrypt\_init**() function initializes a public key algorithm context using key *ctx-\>pkey* for an encryption operation.

The **EVP\_PKEY\_encrypt**() function performs a public key encryption operation using *ctx*. The data to be encrypted is specified using the *in* and *inlen* parameters. If *out* is NULL, then the maximum size of the output buffer is written to the *outlen* parameter. If *out* is not NULL, then before the call the *outlen* parameter should contain the length of the *out* buffer. If the call is successful, the encrypted data is written to *out* and the amount of data written to *outlen*.

After the call to **EVP\_PKEY\_encrypt\_init**(), algorithm specific control operations can be performed to set any appropriate parameters for the operation.

The function **EVP\_PKEY\_encrypt**() can be called more than once on the same context if several operations are performed using the same parameters.

## RETURN VALUES

**EVP\_PKEY\_encrypt\_init**() and **EVP\_PKEY\_encrypt**() return 1 for success and 0 or a negative value for failure. In particular, a return value of -2 indicates the operation is not supported by the public key algorithm.

## EXAMPLES

Encrypt data using OAEP (for RSA keys). See also PEM\_read\_PUBKEY(3) and d2i\_X509(3) for means to load a public key. You may also simply set “eng” to NULL to start with the default OpenSSL RSA implementation:

```
#include <openssl/evp.h>
#include <openssl/rsa.h>
EVP_PKEY_CTX *ctx;
unsigned char *out, *in;
size_t outlen, inlen;
EVP_PKEY *key;
/* NB: assumes that key, in, inlen are already set up
 * and that key is an RSA public key
 */
ctx = EVP_PKEY_CTX_new(key, NULL);
if (!ctx)
	/* Error occurred */
if (EVP_PKEY_encrypt_init(ctx) <= 0)
	/* Error */
if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_OAEP_PADDING) <= 0)
	/* Error */
/* Determine buffer length */
if (EVP_PKEY_encrypt(ctx, NULL, &outlen, in, inlen) <= 0)
	/* Error */
out = malloc(outlen);
if (!out)
	/* malloc failure */
if (EVP_PKEY_encrypt(ctx, out, &outlen, in, inlen) <= 0)
	/* Error */
/* Encrypted data is outlen bytes written to buffer out */
```

## SEE ALSO

EVP\_PKEY\_CTX\_new(3), EVP\_PKEY\_decrypt(3), EVP\_PKEY\_derive(3), EVP\_PKEY\_sign(3), EVP\_PKEY\_verify(3), EVP\_PKEY\_verify\_recover(3)

## HISTORY

**EVP\_PKEY\_encrypt\_init**() and **EVP\_PKEY\_encrypt**() first appeared in OpenSSL 1.0.0 and have been available since OpenBSD 4.9.